To all the 'oh noes - another framework people' - there's a pattern here. We're going through a transition that isn't complete.
(I might have the details wrong but here's the flavour)
Backbone was a good start - Ember and later angular offered to fulfil a genuine need but after a long period of bedding in, many people have become dissatisfied with them.
React (and a few similar frameworks that appeared around thw same time) turned everyone's head and seemed to offer a much better way forward. However it was only part of the jigsaw. It can be described as the V in MVC with some suggestions on the right way to add the M and C ('Flux').
So - what we're seeing now is a lot of people who've had time to digest React+Flux and are releasing a complete MVC package that incorporates all the lessons learnt.
Consider how long we had the "just use jQuery" phase of front-end development. It's just time for pendulum to swing back the other way.